.aside {
  display: flex;
  height: 60vh;
}

.box {
  display: flex;
  flex: 0 0 20%; /* 只占20% */
}

ul {
  li {
    list-style: none;
    font-size: 18px;
    margin: 20px 10px;
  }
}

a {
  text-decoration: none;
  color: black;

  &.active-link {
    font-weight: bold; /* 激活链接的样式 */
    text-decoration: underline; /* 添加下划线 */
    color: green; /* 改变颜色 */
  }
}
